RE: [Dev-C++] Question about structs...

Well, Rob's original code snippet was strict C, so any use of templates
and classes might be outside the scope :-)

The problem with giving advice is always what conceptual level to use.

Template-based code with multiple sort orders normally requires a
smart-pointer implementation, which isn't trivial.

So in this case, a truly general application should probably store the
data in a MySQL database instead, but such a solution is clearly out of
scope of the original question...

About the void. Yes, in C++ it's considered unneccesary noise, best to
leave out of the code. The original use of func(void) was actually a
bit of a kludge to allow parametrized function prototypes in C, as opposed
to the original KR style.

/Per W

On Wed, 23 Oct 2002, Marc Heiligers wrote:

> Hi Per W,
> 
> You're quite right about the GetXXX() methods. Early morning... Coding not
> always best. 
> 
> Ultimately , I would prefer to use a CString class for name and other string
> type properties. Also use TCHAR instead of char, etc. etc. etc. CString
> classes generally have a copy constructor so the result of GetName() would
> not be able to change the value in the instance.
> 
> I did not know that about void. I knew it could be omitted in C++, but is it
> convention to omit it?
> 
> As for the template container, I did say vector or similar. I guess it
> depends on what features you need. Rob was talking about traversing the
> "array" using for loops. I think a vector is quite handy for that. The point
> was to get away from statically defined arrays. 
> 
> _____________________________
> Marc Heiligers
> 
> 
> -----Original Message-----
> From: Per Westermark [mailto:pw...@ia...] 
> Sent: 23 October 2002 02:55 PM
> To: Marc Heiligers
> Cc: 'Rob Peacock'; dev...@li...
> Subject: RE: [Dev-C++] Question about structs...
> 
> 
> What use is a Setname(char *szName) when the GetName() have already sent out
> the pointer to the m_szName array? The GetName() method should be declared
> const char* GetName() const; The First const to say that the returned
> pointer may not be used to change the stored name. The second const to say
> that the GetName() method doesn't change anything inside the class CEmployee
> when called.
> 
> In fact, all GetXX() methods should be written as:
> type GetXX() const;
> 
> Since this is C++, and not C, all methods not taking a parameter should be
> written with empty parentheses. It is only in C, that the void keyword is
> needed.
> 
> If using template containers, it might also be an idea to use the map
> container instead, to allow direct sort and location of entries on customer
> id.
> 
> /Per W
> 
> On Wed, 23 Oct 2002, Marc Heiligers wrote:
> 
> > Hi,
> > If you build an array of structs as you have below, you have a fixed 
> > number of records. It might be a good idea to build your data 
> > structure (and I suggest using a class which you can then use to 
> > validate data and perform operations on your data) and then storing 
> > your "records" in a STL vector, or similar. This allows you to 
> > dymaically change the number of employee, etc. etc. etc. So you'd get 
> > something like:
> > 
> > A file called "employee.h", for example _____________________________
> > #include <vector>
> > 
> > using namespace std;
> > 
> > class CEmployee
> > {
> > public:
> > 	CEmployee();	//constructor - init code
> > 	~CEmployee();	//destructor - clean up code
> > public:
> > 	BOOL SetId(int nId);		//Get and set methods for props
> > 	int GetId(void);
> > 	BOOL SetAge(int nAge);
> > 	int GetAge(void);
> > 	BOOL SetSalary(float fSalary);
> > 	float GetSalary(void);
> > 	BOOL SetName(char *szName);
> > 	char* GetName(void);
> > private:
> > 	//private properties
> > 	int m_nId;
> > 	int m_nAge;
> > 	float m_fSalary;
> > 	char m_szName[25];
> > }
> > 
> > typedef vector<CEmployee*> EMPLOYEES_DATABASE;
> > 
> > _____________________________
> > And then use
> > _____________________________
> > #include <iostream>
> > #include "employee.h"
> > 
> > int main(void)
> > {
> > 	EMPLOYEES_DATABASE database;
> > 	CEmployee *employee = new CEmployee(); 	//Create new employee
> > 	employee->SetName("Marc Heiligers");	//Set employee properties
> > 	employee->SetAge(27);
> > 	employee->SetId(0);
> > 	employee->SetSalary(1000000.00);
> > 	database.push_back(employee);			//Add employee to
> > end of vector
> > 	.
> > 	.
> > 	.
> > 	cout << "Number of employees: " << database.size() << endl;
> > 
> > 	//Use an iterator to loop through all employees and print their 
> > names.
> > 	EMPLOYEES_DATABASE::iterator iter;
> > 	for (iter = database.begin(); iter != database.end; iter++)
> > 	{
> > 		employee = *iter;
> > 		cout << "Name: " << employee->GetName() << endl;
> > 	}
> > 	return 0;
> > }
> > _____________________________
> > So, to answer your question (umm, this may have been a bit of 
> > overkill), yes, you can use employee_name[25] array. You would access 
> > each "record" with a for loop. But there is no need to loop through 
> > the name array unless you want to search the name for a particular 
> > character.
> > 
> > _____________________________
> > Marc Heiligers
> > 
> > 
> > -----Original Message-----
> > From: Rob Peacock [mailto:py...@ea...]
> > Sent: 22 October 2002 06:35 PM
> > To: dev...@li...
> > Subject: [Dev-C++] Question about structs...
> > 
> > 
> > OK, I'm back for more information. I'm looking at a slightly different 
> > way of building the database I asked about yesterday.
> > 
> > The examples I have seen for a structure are typically a database. 
> > Here's the one I have seen posted on several newbie sites:
> > 
> > #include <iostream.h>
> > 
> > struct database
> > {
> >   int id_number;
> >   int age;
> >   float salary;
> > };
> > 
> > int main()
> > {
> >   database employee;
> >   employee.age=22;
> >   employee.id_number=1;
> >   employee.salary=120000.21;
> > 
> >   return 0;
> > }
> > 
> > My question is this; this struct as it is written will only hold one 
> > record, and all of the entries are int's. If I wanted to have multiple 
> > records using the same struct, can I create a struct array (correct
> > terminology?) like this:
> > 
> > struct database[100]
> > {
> >   int id_number;
> >   char employee_name[25];
> >   int age;
> >   float salary;
> > };
> > 
> > To populate it, or to access the individual records within the array, 
> > I would use the standard for() loops, correct? Same with the 
> > emplyee_name[] array?
> > 
> > Thanks all,
> > 
> > --->Rob
> > 
> > 
> > 
> > 
> > -------------------------------------------------------
> > This sf.net emial is sponsored by: Influence the future
> > of Java(TM) technology. Join the Java Community 
> > Process(SM) (JCP(SM)) program now. 
> > http://ads.sourceforge.net/cgi-bin/redirect.pl?sunm0002en
> > _______________________________________________
> > Dev-cpp-users mailing list
> > Dev...@li...
> > TO UNSUBSCRIBE: http://www.noicys.cjb.net/devcpp/ub.htm
> > https://lists.sourceforge.net/lists/listinfo/dev-cpp-users
> > 
>